Patients with systemic lupus erythematosus under the care of NIH will be categorized with 5 categories on the basis of their renal findings. Two groups - those with little or no evidence for renal disease - will be followed systematically. An intermediate group will have kidney biopsy, then be followed systematically and probably be the focus of a therapeutic trial in the near future. A group with serious disease is already the focus of a major therapeutic protocol. Patients with far-advanced disease considered unresponsive to therapy will be referred elsewhere. The major objectives are to collect data systematically on patients with lupus in order to understand the course of illness prior to the development of major renal disease so that it may be prevented.